I'm learning to build an directed graph data structure using adjacency lists, so I thought I'd use LinkedLists to ensure efficient linked list used and I wanted to use an array of Linked list, but I had trouble so I decided to use ArrayList of LinkedList of type Integer, but compiler complains about generics.

The problem I have is having a wrapper that adds a new vertex to the current end of a LL (so it's a wrapper for addLast(Elem e) which is really a LinkedList method)